Express Mach4 4-Blade Stainless Steel Propeller – 15" x 15" | Right Hand Rotation

Express Mach4 4-Blade Stainless Steel Propeller – 15" x 15" | Right Hand Rotation

The Express Mach4 15" x 15" is a high-performance 4-blade stainless steel propeller built for 90–300+ hp engines with 4.75" gearcases. It uses a patented Dual Geometry blade design — two blades optimized for aggressive hole shot and cornering, two blades shaped for high speed and maximum stern lift — delivering the acceleration and handling of a four-blade without the top-end speed penalty typically associated with them.

The 15" diameter with a 15" pitch is a lower-pitch, high-blade-area option well suited to high-torque engines and heavier hulls where getting the boat on plane quickly and maintaining speed under load are the priorities.

Key Features

• Dual Geometry blade design — Two blades use a high-performance variable rake profile for hole shot and cornering; two use an offshore-style design for top speed and stern lift. The result: 4-blade handling with 3-blade top-end speed.
• Proprietary TP17™ stainless steel — 20% higher chromium content than standard stainless for superior corrosion resistance and a higher-gloss finish. Nearly 250% stronger and 5x more durable than conventional stainless steel, enabling more aggressive blade geometries.
• Lifts the hull higher under load — Increased stern lift reduces wetted surface area, minimizing speed loss when the boat is fully loaded with passengers and gear — where a three-blade can lose up to 3 mph.
• Large free-flowing exhaust ports — 40% more exhaust flow area than competing designs reduces backpressure and improves horsepower delivery and hole shot.
• Wide engine compatibility — Fits COX®, Evinrude®, Honda®, Johnson®, Mariner®, Mercury®, MerCruiser®, Nissan®, OMC®, OXE®, Parsun®, Suzuki®, Tohatsu®, Volvo Penta®, and Yamaha® outboards and sterndrives.

Specifications

• Diameter x Pitch: 15" x 15"
• Blades: 4
• Material: TP17™ Stainless Steel
• Rotation: Right Hand (Standard)
• Gearcase Fit: 4.75"
• Engine Range: 90–300+ hp
• Hub System: 500 Series (under 200 hp) or 700 Series (200+ hp) — sold separately

Hub Kit Required

A MasterGuard installation hub kit is required and sold separately. Use the 500 Series for engines under 200 hp, or the 700 Series for engines 200 hp and above. Mercury Verado® and ProXS® owners with a 1.25" fat shaft will need the MasterTorq® 621 FSH Fat Shaft Hub Kit instead. Refer to the application chart for your engine’s required kit number.

• MasterGuard Hub Kit 500 – 500 Series
• MasterGuard Hub Kit 502 – 500 Series
• MasterGuard Hub Kit 506
• MasterGuard Hub Kit 508
• MasterGuard 700 Series Hub Kit – 200+ hp

Also Available

• Express Mach4 15" x 15" – Left Hand (Counter) Rotation
• Express Mach4 14" x 19" – RH (4.75" Gearcase)
• Express Mach4 14" x 21" – RH
• Express Mach4 14" x 23" – RH
• Express Mach4 15.3" x 13" – RH (4.75" Gearcase)
• Express Mach3 14.25" x 19" – 3-Blade Stainless RH

Parts Desk Insights

Best use case: The Mach4 15" x 15" is the right call for high-horsepower applications (90–300+ hp) where the customer needs the best combination of hole shot, stern lift, and load-carrying performance from a stainless prop. The lower 15" pitch with a wide 15" diameter makes it particularly effective on heavier hulls, high-torque engines, or boats that regularly carry full loads — watersports, tri-toons, bay boats, and sterndrives are ideal applications. The Dual Geometry design means it won’t sacrifice top-end speed the way a conventional 4-blade would. If the customer’s priority is pure top-end speed on a lightly loaded boat, the Mach3 3-blade at a higher pitch may be worth comparing. For twin-engine setups, confirm whether a counter-rotation (LH) version is needed — the 15" x 15" LH is available. Always confirm engine make, model, year, gearcase size, and current WOT RPM before finalizing a prop recommendation.